There is zero reason we don't send "auditors" thru the prison system to ensure everything is above board.
Some random ass places in Kentucky did it for years for a reality show. Send them in like they're doing a random stretch and let them stay for even just a month and they'd get a feel for the place.
It's not even like it needs to happen often, just the chance of it would be beneficial.
And before anyone can say "it's too dangerous", if it's too dangerous for this how the fuck are criminals supposed to get rehabilitation in that environment?